Problem: Eliana drove her car $81 \text{ km}$ and used $9$ liters of fuel. She wants to know how many kilometers $(x)$ she can drive on $22$ liters of fuel. She assumes her car will continue consuming fuel at the same rate. How far can Eliana drive on $22$ liters of fuel?
Solution: We're dealing with a proportional relationship, so each ratio of kilometers to liters must be equivalent. We can represent this relationship in a table. Kilometers (km) Liters (L) $81\text{ km}$ $9\text{ L}$ $x\text { km}$ $22\text { L}$ We can use the table to solve for $x$ : ${x}$ $\longrightarrow$ ${22}$ ${81}$ $\longrightarrow$ ${9}$ $ \times {\dfrac{22}{9}}$ $ \times {\dfrac{22}{9}}$ ${{km}}$ $\longrightarrow$ ${{L}}$ We need to multiply $81\times \dfrac{22}9$ to find $x$. $81\times \dfrac{22}{9} =\dfrac{ \stackrel{9}{\cancel{81}} \times~ 22 }{ 1 \times\underset{1}{\cancel{9}}} =\dfrac{198}1=198$ Eliana can drive $198\text{ km}$ using $22$ liters of gas.